Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02307063 2000-04-28
SYSTEM USING ANTHROPOMETRIC FRAME FOR MEASUREMENT OF BONY
SPATIAL RELATIONSHIPS
Field of the Invention
The invention relates to a system using an anthropometric frame
which allows measurements of the spatial relationship between bony points on
animals such as the measurement of bony pelvic landmarks and the stance
position of humans.
Background of the Invention
Skeletal asymmetry has been frequently associated with altered
function and is frequently thought to be a contributing factor in a variety of
pain
syndromes attributed to asymmetry within the musculoskeletal system, for
example, low back pain in humans. Many of these musculoskeletal problems
account for enormous costs both directly - time off work and compensation for
the sufferer - and indirectly - lost productivity. To a very great extent,
current
practice relies on the use of subjective measurements for decisions on
interventions and care and objective outcome measures are scarce or lacking.
It
is of particular interest that this widespread subjective approach is
particularly
noticeable in the literature describing therapeutic interventions for
relatively minor
asymmetries. It is abundantly clear that objectivity of measurement,
therapeutic
planning and measurement of outcome are lacking.
Subjective examination of skeletal asymmetry in human subjects is
frequently performed by visual-palpatory assessment of the whole body and
selected parts. Although tape measures and goniometers are frequently employed
in an attempt to provide more objectivity, these techniques have been shown to
lack reliability and validity. The usual gold standard for the measurement of
skeletal asymmetry entails the use of ionizing radiation, for example
radiology,
however, these procedures are expensive, time consuming and potentially
hazardous to health. It is also important to recognize that measurements of
pelvic
asymmetry taken by most clinicians/researchers typically are restricted to
front
(anterior), or back (posterior), or front to back (antero-posterior or pelvic
tilt)
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which do not give an accurate 3-dimensional description.
Accordingly, a system and a related frame for the accurate
measurement of bony spatial relationships is needed. It will be of value for
health
practitioners such as orthopaedic surgeons, physiotherapists, chiropractors,
osteopaths who diagnose and treat asymmetries and for technicians involved in
the design and construction of lower limb prostheses and orthoses.
Summary of the Invention
The system of the invention uses a frame having stability and rigidity
sufficient that accuracy of measurement, combined with minimum wear and tear,
are maintained.
The invention in one broad aspect pertains to an anthropometric
frame system comprising a base, a foot frame device for selectively measuring
or
placing feet of a subject in a preferred or selected stance orientation on the
base
and an orthogonal frame device for measuring the spacial relationships of
various
bony points on the subject's body. The orthogonal frame device comprises
means mounted to the base for horizontally supporting a crossbar in selected
vertical positions, the crossbar having means for supporting a first
measurement
device for lateral measurements. The crossbar also includes means for
supporting
a second measurement device for vertical measurements and the means for
supporting the second measurement device also supporting a third measurement
device for front to back measurements whereby orthogonal spacial relationship
between bony points on a subject's body can be measured. The foot frame
device is selectively positioned on the base relative to the orthogonal frame
device
whereby orthogonal measurements are taken when the subject is in the preferred
or selected stance orientation in the foot frame.
The invention in another aspect pertains to a method of measuring
the spacial orthogonal relationships between selected bony points on a
subject,
comprising the steps of (a) providing an anthropometric orthogonal frame
system
comprising a base and a foot frame device and an orthogonal frame device
selectively positioned on the base, the orthogonal frame device comprising
means
mounted to the base for horizontally supporting a crossbar in selected
vertical
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positions, the crossbar having means for supporting a first measurement device
for lateral measurements and the crossbar including means for supporting a
second measurement device for vertical measurements and the means for
supporting second measurement device also supporting a third measurement
device for front to back measurements, the third measurement device including
a
pointer and the foot frame device configured to permit placing of feet of the
subject in a preferred or selected stance orientation on the base, (b)
locating the
feet of the subject on the base in association with the foot frame device, (c)
locating the crossbar at a selected height relative to the area of the subject
to be
measured, (d) locating the pointer associated with the third measurement
device
at a desired location on the subject and recording measurements from at least
two of the first, second and third measurement devices, (e) locating the
pointer
associated with the third measurement device at a second desired location on
the
subject who remains stationary in the same position as when the first
measurements were recorded (f) recording the second measurement and (g)
determining the spacial relationship between the first and second locations
from
the measurements recorded.
The system preferably includes a frame system having two
components or devices with an optional component to the system.
The first component, device or part of the system is an adjustable
foot frame device on a base which can be used to measure the subjects
preferred
stance orientation or which may be used to place the subject in a
predetermined
stance position facing forwardly or backwardly.
The second component, device or part of the system is an
orthogonal frame device comprised of a 3-dimensional measurement component,
(3-D componentl, which is mounted on two vertical poles which readily permit
the
3-D component to be adjusted to different levels on the poles specifically so
that
the system can accommodate individuals from varying height groups. This part
of
the system determines the dimensions of the control volume. The measurement
scales are preferably metric and all adjustable parts have locking screws.
The optional component or part of the system is preferred for the
measurement process. A simple adjustable support such as a walking frame,
(like
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those readily found in most clinics and nursing homes), is used to control the
subject's postural sway and provide stability during the measurement process.
However, other forms of like supports are possible.
More particularly, the system is preferably mounted on a solid base
having an upper surface which can be easily cleaned and has a grid marked
thereon. The base is equipped preferably with levelling screws or like means
so
that it can be levelled if the floor or other surface on which it is located
is not
level. The base can include visual aids for levelling the base or such aids
can be
separate.
The foot frame mounted on the base permits measurement of a
subject's preferred foot position or to set a prescribed foot position, that
is, the
stance angle and distance between feet. The foot frame is comprised of a
horizontal bar and two outer bars adjacent the base, the horizontal bar being
moveable forward and back relative to the base and grid thereof.
The two outer or lateral bars are pivotally and slidably connected at
one end of the outer bars to the horizontal bar.
Although protractors can be attached where each outer bar is
pivotally connected to the horizontal bar to measure a stance angle, the use
of
separate protractors is an alternative.
The 3-D component comprises two laterally spaced, vertical poles
located towards the front of the base and are marked with identical
measurement
scales. A horizontal bar is vertically adjustably mounted to the two poles.
Three
precision orthogonal measuring devices are adjustably mounted to the
horizontal
bar. The precision measuring devices are used to measure differences in front
to
back, up and down and side to side distances.
The optional support frame is height adjustable and designed for
stabilizing the subject and restricting postural sway during testing and
measurement. Such a device can be incorporated with the base but a single
adjustable walker frame is usable and therefore the support frame is optional
as a
component necessarily connected to the base.
The system is designed to be consistently accurate, robust and
stable, relatively inexpensive, non-invasive (ionizing radiation free) and
with
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reasonable portability within a clinical facility. It is easy to use and
provides the
clinician or researcher with immediate and accurate data for diagnostic and
follow-up assessments. Calculations of the ratios which define different
pelvic
skeletal asymmetries can be very quickly obtained, require very simple
mathematics and are readily derived from anterior and posterior measurements
alone.
The purpose of the system, including the components, is to provide
objective and accurate measurements of the spatial relationships between bony
points on human subjects. Although it has been designed specifically for the
measurement of bony pelvic landmarks and stance position, the frame could be
adapted for other human body measurements. There is a distinct advantage of
having a relatively small control volume in which highly accurate measurements
can be taken, especially when the control volume can be moved into different
positions to accommodate for individuals of widely differing height and for
selected body measurements.
The frame was tested for accuracy and found to be accurate to 1.0
mm within a typical measurement volume, or control volume, of approximately 40
cm width x 20 cm height x 15 cm depth. A control volume establishes the
outermost boundaries for accurate measurements. Adhesive markers are placed
on the subject for identification of the bony points and for the measurements.
This method has also been statistically tested in the lab and shown to be
highly
reliable for the accuracy of repeated marker placements and measurement. The
obtained raw measurements are used to calculate asymmetry ratios, thus
providing normalized data which can be used to make objective comparisons
between subjects.
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Brief Description of the Drawings
FIG. 1 is a front objective view of the frame of the invention with a
foot component and a 3-dimensional measurement component, (3-D component),
of the system, both associated with a base support.
FIG. 2 is a partial sectional view taken along line 2 - 2 of FIG. 1
showing the lock screw and slot connection of the frame of foot component with
the base.
FIG. 3 is a partial sectional view taken along line 3 - 3 of FIG. 1
showing the lock screw slot connection of the lateral or outer bars of the
foot
frame with the main bar of the foot frame.
FIG. 4 is a sectional view of the connection between the bar of the
3-D component and a vertical post taken along line 4 - 4 of FIG. 1.
FIG. 5 is an enlarged view of a portion of the 3-D component as seen
in FIG. 1.
FIG. 6 is a left side view of the 3-D component.
FIG. 7 is a sectional view of the connection of the pointer ruler taken
along line 7 - 7 of FIG. 6.
FIG. 8 is a top view of the foot frame showing a subject's stance
position.
FIG. 9 is an oblique view of the measurements of markers on the
back of a subject for posterior analysis.
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Description of the Preferred Embodiments of the Invention
Referring to Figure 1, the inventive anthropometric frame 20 is
shown with foot or stance component 24 and 3-dimensional component, (3-D
component), 26 on base 30.
Base 30 is a sheet of material such as wood or plastic with levelling
screws 32 at each corner 34 whereby base 30 can be levelled on a support
surface such as the floor 38. Base 30 has an upper surface 40 covered with
material capable of being easily cleaned and on which a grid can be formed.
Surface 40 preferably is a laminex surface with a matrix grid 42 of preferably
one
centimeter squares marked thereon, only a small portion of grid 42 being
shown.
Turning more particularly to Figures 1, 2, 3 and 8, foot or stance
measurement component 24 comprises a bar 50 which is slidingly mounted to
base 30 through a locking screw 54 and associated slot 56 in base 30. Bar 50
is
selectively moveable in a forward or rearward movement and can be detachably
secured in a selected position by the lock screw 54 in cooperation with slot
56 as
illustrated in sectional view in Figures 2 and 8.
Lock screw 54 is typical of the other lock screws referred to herein
including wing nut 60, threaded shank 62 and circular head 64 adapted to run
in
elongate recess 68 of the slot 56 as shown in Figure 2.
Laterally spaced bars 70, 72 are pivotally connected adjacent ends
74, 76 respectively to bar 50 and can be moved laterally inwardly or outwardly
along respective portions of bar 50 through a lock screw 78, 80 and slots 82,
84
respectively. Figure 3 is a partial sectional view along lines 3 - 3 of Figure
2
showing the connection of bar 70 with bar 50, the connection of bar 72 being
similar to that of bar 70. Winged screw 78 includes shank 56 extending through
bore 88 in bar 70 and slidably received in slot 82 of bar 50, with head 90
running
in elongate recess 92 in bar 50.
The purpose of the foot component 24, (as seen in Figure 8), is to
permit measurement of a subject's preferred foot position or to set a
prescribed
foot position (stance angle and distance between feet). The foot component 24
is comprised of the horizontal bar 50 and the two outer bars 70, 72. The
horizontal bar being adjustable forwardly and rearwardly in slot 56 in the
centre of
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the base 30. Bar 50 can be set in line with the marker grid 42 on the base 30
or
at any selected angle. Each outer bar 70, 72 may be adjusted towards or away
from the centre of the horizontal bar, in respective slots 82, 84 in
horizontal bar
50. Protractors may be attached where each outer bar is pivotally mounted to
the horizontal bar to measure the stance angle denoted A and B in Figures 1
and
8. Alternatively, protractors may be used separately. It should be noted that
the
foot frame device 24 may be rotated 180° about pivot 54 so that the
stance
orientation may be set the same for both anterior and posterior measurements
with the orthogonal frame device.
Turning particularly to Figures 1, 4 - 7 and 9, the 3-D frame 26
comprises laterally spaced rigid poles 100, 102 vertically mounted to base 30
through collars 104, 106 respectively, poles 100, 102 being mounted
perpendicular to and towards the front of base 30, (collars 104, 106 are in
the
form of threaded pipe sockets or plain sockets with locking screws). Poles
100,
102 are marked with identical measurement scales 108, only parts of which are
shown. It will be appreciated that poles 100, 102 can be detachably mounted to
base 30 but in any event, poles 100, 102 are precision mounted so that the
vertical measurements scale 106 on each pole will be in lateral (horizontal)
alignment.
Rigid horizontal bar 110 is mounted for selected vertical movement
relative to vertical poles 100, 102 through blocks 112, 1 14 and a combination
lock wing nut screw 120 and block bore 122 as shown further in sectional view
in Figure 4, screw 120 having shank 124 threaded in bore 126 of block 114.
It will be apparent however that any other mechanism to mount bar
110 horizontal to poles 100, 102 so that bar 110 is movably secured to poles
100, 102 is appropriate, including poles with a slot therein.
A first measurement device 130, more particularly shown in Figure 5,
includes a horizontally movable first sliding block 132 having a U-shaped
cross-
section for riding on bar 1 10 with a lock screw 136 capable of securing block
132 at a selected location on bar 110. A spring loaded tape measure 140 of
usual construction with outer tape end 142 is securely mounted on block 132.
Further, a second sliding block 150, also U-shaped in cross-section, (see
Figures 5
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and 9), is slidably mounted on bar 110, second sliding block 150 having lock
screw 154 whereby block 150 may be positively secured in a selected position
on
bar 1 10. End 142 of tape measure 140 is detachably fastened in catch 156 of
block 150 whereby movement of sliding block 150 on bar 110 relative to block
132 causes tape measure 140 to extend or retract depending on the direction of
relative movement between block 150 and block 132.
Turning to Figures 6 and 7, a second measurement device 160
comprises a vertically scaled pole 162 fixed to and extending vertically
upwardly
from sliding block 150, pole 162 having metric scale 164 thereon, only part of
which is shown.
Further, block 170, having throughbore 172, is mounted on pole 162
for selective sliding movement along pole 162, with lock screw 174 selectively
securing block 170 at desired positions on pole 162.
A third measurement device 180 comprises pointed horizontally
disposed ruler 182 being selectively secured in slot 184 in block 170 in a
desired
position by a clear plastic cover 186 secured by four locking screws 192.
Threaded lock screw 194 has head 196 and its shank end 198 can be pressed
against ruler 182 to hold it in a selected position within slot 184.
Alternatively a
tight sliding fit between slot 184 and ruler 192 is possible. Ruler 182 has
ruler or
scale 188 thereon (partly shown) and pointed outer end 190.
Accordingly, the 3-D component 20 provides three orthogonally
mounted and adjustable measuring devices attached to horizontal bar 1 10,
namely
a first device 130 to measure the differences side to side, a second device
160 to
measure the differences up and down and a third device 180 to measure
differences from front to back.
Further particulars with respect to the measurement, (anterior
measurements) and use of the 3-D component of the frame and system follow.
Assume that a subject has two anterior markers, one each on the left
and right side of the pelvis and the person is standing on the base board
facing
towards the front of the system and the tester, i.e. looking forwardly from
Figure
1 and as the feet are shown in Figure 8.
Step 1. The stance/foot position is measured or set to a prescribed
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position with frame device 24. (See Figure 8).
Step 2. A walker frame (or similar support, the third component) is
brought up behind the subject and the individual is instructed to steady
themselves by holding onto the walker frame without taking weight through the
arms.
Step 3. The horizontal rigid bar 110 is placed about level with the
hip joint, checked for level and the locking screws 120 tightened.
Step 4. Lock screw 1.94 on clear plastic cover 186, lock screw 174
on block 170, lock screw 136' on the first sliding block 132 and the lock
screw
154 on the second sliding block 150 respectively are slackened.
Step 5. The end 190 of horizontal pointer rule 182 is aligned with
the bony point marker on the left side of the subject (testers right), as
looking at
Figure 1, ensuring that both first and second sliding blocks 132, 150 are
together
(in this position the spring loaded tape measure 140 will be at zero). Lock
screws
136, 154, 174 and 194 are then tightened.
Step 6. The height of the subject's left marker and distance from
the frame are recorded from scales 162 and 188. These positions are used as
the
reference point for subsequent measurements.
Step 7. The pointer 190 is then retracted from the subject by
loosening cover lock screw 194 and lock screws 154 and 174, (but not lock
screw 136 of first sliding block 132). The second sliding block 150 (on which
the vertical pole 162 and horizontal ruler 182 are mounted) is then moved to
align
with the subject's right side marker, (left side of tester) and the locking
screws
154, 174 and 194 are tightened. The first block 132 remains in situ. The
height
of the subject's right side marker and distance from the frame are then
recorded
and the width apart of the markers can be simultaneously recorded because the
spring loaded tape measure 140 will have been extended by the exact same
amount.
Step 8. Using the asymmetry ratio method, the height difference
divided by the width separation of the markers will give the anterior
asymmetry
ratio which is the gradient (slope) or tangent of the angle to the horizontal
between the two markers.
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As well, the actual measurements from the floor to each marker can
be recorded from scale 106 combined with scale 164.
Step 9. A similar procedure is repeated for the posterior
measurements with posterior markers 200, 202 as shown in Figure 9.
More particularly, lock screw 54 on foot frame device is loosened
and the foot frame, with orientation of bars 70 and 72 fixed in the same
orientation as shown in Figure 8, is rotated 180°. The subject's feet
are then
located within the foot frame device with the same stance and angular
orientation
as they were in during the anterior measurements. With the subject 210 now
facing the back of the device as shown in Figure 1, skin markers 200, 202,
(Figure 9), are applied to a bony projection on the back of each hip.
Accordingly,
relative front to back distances of the bony points are recorded from the
pointed
ruler 182, the point 190 of which is brought close to and aligned first with
the
skin marker 200. As ruler 182 can be moved up or down on vertical pole 162,
the scale 164 on pole 162 is used to measure comparative heights when end 190
of ruler 182 is aligned with other bony points, such as the one identified by
marker 202. With block 132 secured in the position where the first body marker
200 was recorded, block 150 can be slightly adjusted on bar 110 to permit
ruler
pointer 190 to be aligned with the opposite side body marker 202 and the
distance between the blocks 132 and 150, which is exactly the same as the
horizontal distance between the body markers 200, 202, can be recorded from
the tape measure 140. The differences in height between the markers 200, 202
can also be measured using scale 164 on pole 162. Figure 9 also shows the arms
212, 214 of a walker used by the subject 210 to steady him/herself as noted
above in Step 2 for anterior marker measurements.
Thus, using asymmetry ratios, objective comparisons between the
spatial relationships of the anterior, posterior, right and left halves of the
selected
bony points of the pelvis can be made and the spatial relationship between the
stance position and pelvic asymmetry can be determined.
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